Redesign of a Safety Syringe

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Redesign of a Safety Syringe
University of Pittsburgh Senior Design BioE
1160/1161
Jessica Chechak Jason Keiser Ellsworth
Weatherby April 18, 2005
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Presentation Overview

• Problem Statement
• Proposed Solution
• Specific Aims
• Design Considerations
• Design Requirements
• Design Process
• Initial Design
• Final Design
• Design Review
• Prototype Fabrication
• Functionality Testing

• Quality Systems
• Manufacturability
• Human Factors
• Regulatory
• Economic Considerations
• Project Timeline
• Group Responsibilities
• Ellsworth
• Jason
• Jessica

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Problem Statement

• There are approximately 236,000 percutaneous
  injuries resulting from accidental needlesticks
  every year
• 50 of injuries occur between the time the
  procedure is completed and disposal of the device
• 20 are associated with disposal of the device
• Needlestick injuries expose health care workers
  to diseases caused by bloodborne pathogens
• AIDS (from HIV)
• 0.001 probability of contracting per needlestick
• hepatitis B (from HBV)
• 0.126 probability of contracting per needlestick
• hepatitis C (from HCV)
• 0.024 probability of contracting per needlestick
• Adoption of needles with safety features would
  prevent about 69,000 needlesticks each year

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Proposed Solution

• We propose the creation of a single use safety
  syringe that includes several categories of safer
  device features
• Retractable Needle
• Sliding Sheath
• Screw-on cap
• This novel design combines several safety
  features to satisfy FDA guidelines
• These engineering controls effectively reduce the
  risk of an exposure incident in several sites

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Specific Aims

• Modify current safety syringe designs to
  increase safety to the user as well as anyone who
  is exposed to the syringe.
• Our proposed design contains aspects of several
  marketed designs, along with a few new features
• Current models may have an exposed needle or a
  retractable needle that can leak both are
  biohazards.
• The combination of a retractable needle, needle
  shield and screw on cap will prevent needle-stick
  injury and leaking of biohazardous materials
  before and after use.
• The combination of safety features will ease
  disposal and prevent reuse.

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Specific Aims

• Fabricate a sufficient number of prototypes to
  support Phase I functionality testing.
• The design was drafted in SolidWorks
• The body of the syringe was produced with a
  rapid-prototyper thorough the process of
  Stereolithography (SLA).
• The parts were hand-assembled by the Design
  Coordinator using a documented process.
• Several variations of the design were prototyped
  to assure best fit, and to experiment with
  various materials

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Specific Aims

• Test the Phase I prototypes, in vitro, to
  demonstrate basic functionality.
• The research team used an in vitro testing
  apparatus to test the syringes.
• Tests will show that the prototype successfully
  meets the functionality standards set forth by
  the team
• no leakage pre-use or post use
• successful fluid delivery
• a retractable needle

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Initial Design Considerations

• FDA Guidelines
• 29 CFR part 1910.1030, The Bloodborne Pathogens
  Standard
• Enforced by OSHA through citations and fines
• Injuries Statistics
• 236,000 needlesticks/year
• Every year about 1.3 million people die of blood
  infections caused by the re-use of syringes
• Consequences of needlesticks
• Disease transmission
• Post-exposure prophylaxis 500-1,000 per
  injury
• 1.7 million workers needed time off to recuperate
  after incidents

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Safety Syringe Design Requirements

• Our design goals were to achieve every FDA
  recommended design feature characteristic of a
  safer device
• Provide a barrier between the operator's hands
  and the needle after use
• Will allow the operator's hands to remain behind
  the needle at all times
• Be an integral component of the device, and not
  an accessory
• Provide protection before, during and after use
  and after disposal
• Be simple and self-evident to all operators and
  require little training and no particular
  expertise

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Design Process Initial Design

• The initial design utilized a push button to
  retract the protective shield.
• This facet was redesigned to reduce the
  complexity of the design and to reduce the cost
  of mass manufacturing.
• The retractable needle mechanism was initially
  activated when the plunger reached the bottom of
  the syringe body.
• This was modified to make the retractable needle
  mechanism user activated.
• Initially the syringe was intended to be
  pre-filled this modification allowed the syringe
  to be sold unfilled.

Design Mid-December
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Design Process Final Design

• The protective shield was designed to allow the
  user to slide it up and down the syringe body
  without having to compress a button, thus
  simplifying the device.
• The retractable needle is activated by a spring
  loaded mechanism located in the luer of the
  needle.
• This system is triggered by a 5lb downward force
  on the plunger by the user after the medication
  has been delivered.
• The protective cap remains locked into position
  before and after use until a force of 1lb is
  applied.

Final Design Before Use
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Final Design Intended Use
Ready To Inject
Before Use
Ready For Disposal
After Use
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Design Review
Syringe Body
Are the dimensions in mm? Yes
Does the body fit into the protective shield? Yes
Does the syringe body have a 9mm opening for the plunger? Yes
Does the syringe body bottom opening have a luer thread pattern comforming with ISO 594-11986 "Female Fittings"? Yes
Does the body have an opening to lock-in the push button mechanism? Yes
Protective Shield
Are the dimensions in mm? Yes
Does the protective shield fit over the syringe body? Yes
Does the shield have a luer thread pattern on the ouside end conforming to ISO 594-21998 "Male Fittings"? Yes
Does the shield have a square pattern on the top for use with the push button? Yes
Does the luer threading and shield fit into the Protective Cap? Yes
Protective Cap
Are the dimensions in mm? Yes
Does the Cap have a luer thread pattern on the inside conforming to ISO 594-11986 "Female Fittings? Yes
Does the luer threading and cap fit onto the protective shield? Yes
Backing Pad
Are the dimensions in mm? Yes
Does the backing pad fit against the back of the protective shield? Yes
After all questions were answered Yes
prototyping began.
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Prototype Fabrication

• The prototype was produced by quickparts.com
• Solidworks files of the design were used
• Stereolithography (SLA) rapid prototyping was
  used to produce the parts
• The initial prototypes were made of Somos 14120
  (a low viscosity photopolymer white color)
• Issues with tolerances and angle of threads
• A second set of prototypes was made also using
  Somos 14120
• Parts were assembled, fit was good, but thread
  angle needed to be changed
• A final set of prototypes was made of Somos
  11120 (a low viscosity photopolymer clear
  color)
• New material had different tolerances, but we
  were able to combine parts to produce the final
  prototypes

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Prototype Intended Use
Before Use
Ready To Inject
Ready For Disposal
After Use
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Comparison to Current SyringesBefore and After
Use
Our Hybrid Safety Syringe
Protective Shield Safety Syringe
Retractable Needle Safety Syringe
Normal Syringe (Non-Safety)
Before Use
After Use
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Functionality Testing

• Functionality testing was performed to
  demonstrate that the syringe met the standards
  for success
• No leakage pre-use or post use
• Successful fluid delivery
• A retractable needle
• Operational needle shield
• Operational screw-on cap

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Quality Systems Considerations

• Manufacturability
• Simple Design
• Needle is surgical grade stainless steel
  (standard size 23 gauge)
• Plastic components will be made from PTFE and
  polypropylene
• Rapid Injection Molding will be used for
  production of plastic components
• Human factors
• Ease of use
• Biocompatability of components
• Non-Allergenic components
• Easily disposable Biohazard safe

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Quality Systems Considerations

• Regulatory
• 29 CFR 1910.1830 - Bloodborne Pathogen standard
• The Occupational Safety and Health Administration
  (OSHA) promulgates a standard to reduce
  occupational exposure to bloodborne pathogens
  through a combination of
• Engineering controls
• Work practice controls
• Enforcement Procedures
• Show evidence of adoption of devices/engineering
  controls that reduce exposure
• Document plan annually and any difficulties
• Inspections complaints some scheduled
  inspections
• OSHA does not require a specific device

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Quality Systems Considerations

• Regulatory (cont.)
• The Needlestick Safety and Prevention Act
• Directed OSHA to revise the bloodborne pathogen
  standard
• New definitions in engineering controls
• Sharps with engineering sharps injury protection
• Needless systems
• Annual review/update of exposure control plan
• Employers are required to select safer needle
  devices as they become available
• Involve frontline workers in device selection
• maintain detailed sharps injury log
• The Centers for Disease Control and Prevention
  estimated in March 2000 that selecting safer
  medical devices could prevent from 62 to 88
  percent of sharps injuries in hospital settings.

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Economic Considerations

• Cost of Safety devices
• 1 to 3.5 times more than conventional devices
• The increased purchase costs of using needles
  with safety features would be between 70 million
  and 352 million per year.
• Cost of Post-Exposure Prophylaxis
• 500 low 1,500 moderate 2,500 high risk
• Eliminating 69,000 needlesticks per year would
  reduce post-exposure treatment costs for by
  between 37million and 173 million per year.
• Market size
• 550M per year (US hospital patients)
• Frost Sullivan (www.chetday.com/me
  dmistakes.html)
• Distribution
• Hospitals, Individuals

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Cost Effectiveness of Safety Devices
Cost of safety devices are offset by cost of
post-exposure prophylaxis and follow up in medium
and high-risk scenarios
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Projected Project Timeline
This is our initial project timeline. We remained
on schedule within a day or two of our initial
project deadlines. We received our initial
prototype earlier than expected. This gave us
time for several redesigns to produce the final
prototype.
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Group Responsibilities

• Ellsworth Business Manager / Safety Coordinator
• Jason Design Coordinator
• Jessica Project Coordinator

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Ellsworths Achievements

• Business Manager
• Research on Market Size etc.
• Creation of final PowerPoint presentation
• Updating controlled documents

• Safety Coordinator
• Research on OSHA standards for Safe Sharps
• Writing Section B of the SBIR Phase I Application

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Jasons Achievements

• Design Coordinator
• Modeling of design in Solidworks
• Design modifications
• Design Review
• Prototyping
• Functionality Testing
• Writing Section D of the SBIR Phase I Application

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Jessicas Achievements

• Project Coordinator
• Scheduling Team meetings
• Creation of final PowerPoint presentation
• Writing Sections A and C of the SBIR Phase I
  Application
• A Specific Aims
• C Relevant Experience / Preliminary Work /
  Design Review
• Editing the SBIR Phase I Application
• Updating Controlled Documents

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Any Questions?
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Hypodermic syringes with Needle-Sheath safety
feature

• Active Safety Feature
• A feature that requires the operator to
  activate the safety mechanism, and failure to do
  so leaves the operator unprotected

Needle-sheath syringe
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Hypodermic syringes with Retractable Technology
safety feature

• Passive Safety Feature
• A safety feature that remains in effect before,
  during and after use, the operator does not need
  to "activate" the safety feature
• Integrated Safety Design
• The device has the safety feature included into
  its design and it can not be removed or
  inactivated. This is the preferred safety
  feature.

Retractable needle safety syringe